Asynchronous JavaScript

Asynchronous JavaScript is a core programming paradigm that addresses the language's single-threaded nature, allowing it to handle long-running operations without blocking the main execution thread. By using features like callbacks, Promises, and the modern `async`/`await` syntax, developers can initiate tasks such as network requests, file I/O, or timers, and then allow other code to run while waiting for those tasks to complete. This non-blocking model is fundamental to creating responsive user interfaces and efficient, scalable applications, especially in environments like web browsers and Node.js where waiting for I/O operations is common.

1. Foundations of Asynchronous JavaScript
   1. Synchronous vs. Asynchronous Execution
      1. Definition of Synchronous Execution
      2. Definition of Asynchronous Execution
      3. The Single-Threaded Nature of JavaScript
         1. JavaScript Engine Architecture
         2. Implications for Code Execution
      4. Blocking Code Examples
         1. Synchronous Loops
         2. Synchronous Network Requests
      5. Non-Blocking Code Examples
         1. Asynchronous Timers
         2. Asynchronous Network Requests
   2. The JavaScript Concurrency Model
      1. The Call Stack
         1. Function Invocation and Execution Contexts
         2. Stack Overflow and Recursion
      2. The Web APIs (Browser Environment)
         1. Timer APIs
         2. DOM Events
         3. AJAX and Fetch
      3. C++ APIs (Node.js Environment)
         1. File System Operations
         2. Network Operations
      4. The Callback Queue (Task Queue)
         1. Definition and Role
         2. Types of Tasks
            1. setTimeout Tasks
            2. setInterval Tasks
            3. I/O Tasks
      5. The Microtask Queue
         1. Definition and Role
         2. Sources of Microtasks
            1. Promises
            2. MutationObserver
            3. queueMicrotask
         3. Priority over Task Queue
   3. The Event Loop
      1. Role and Function
         1. Monitoring the Call Stack and Queues
         2. Moving Tasks from Queues to Call Stack
      2. Processing Order
         1. Microtasks vs. Macrotasks
         2. Microtask Execution After Each Task
         3. Starvation of Task Queue
      3. Visualizing the Event Loop
         1. Step-by-Step Execution Flow
         2. Common Diagrams and Tools
      4. Event Loop in Browsers vs. Node.js
         1. Differences in Implementation
         2. Node.js Event Loop Phases
            1. Timer Phase
            2. Pending Callbacks Phase
            3. Idle and Prepare Phase
            4. Poll Phase
            5. Check Phase
            6. Close Callbacks Phase